裂纹间作用机制探讨及微裂纹区对主裂纹的作用效应研究

采用迭加原理和Kachanov提出的简化方法，研究了裂纹间的相互作用机理，分析了不同裂纹布置形式所产生的增强或屏蔽效应，发现当微裂纹沿着或垂直于最大拉应力方向布置时都不产生最大的作用效应，这有别于Ortiz的结论．还探讨了混凝土类材料的微裂纹的产生机制及微裂纹区对主裂纹尖端产生的作用效应，得出微裂纹区对主裂纹是起增强的作用，增强程度随微裂纹密度和微裂纹长度的增大而增大的结论．

Interaction Between Cracks and Effect of Micro-Crack Zone on Main Crack Tip

The mechanism interaction between cracks with different orientations was analyzed based on the principle of superposition and a flattening method.It is found that the maximum interaction effect will not occur when the micro crack is along the direction parallel or perpendicular to the principal tensile stress,which is different from the conclusion drawn by Ortiz [ASME Journal of Applied Mechanics,1987,54(3):54-58].The production mechanism of microcrack and the effect of microcrack zone on main crack tip were also studied.As a result,the microcrack zone has magnifying effect on main crack tip,and such a magnifying effect increases with the increase of micro crack density and length.